Aerobic Exercise for the Older Brain

Animal research and observation studies in humans point to an association between exercise—particularly aerobic cardiovascular exercise—and enhanced brain health that may reduce the risk of dementia or slow its progression. Given that there are no disease-modifying or preventive therapies for Alzheimer disease (AD), exploration of the impact of aerobic exercise on dementia has become a popular avenue of research. Recent findings from researchers affiliated with the University of Kansas in Kansas City suggest that aerobic exercise helps improve functional ability and reduce hippocampal atrophy in early-stage AD.1

The researchers conducted a pilot study to assess the effect of 6 months of supervised aerobic exercise on memory, executive function, functional ability, and depression in 68 adults (average age, 73 years) with a diagnosis of mild cognitive impairment or probable AD. Secondary outcomes included cardiovascular fitness and impact on brain structure.

Participants randomized to the aerobic therapy group were supervised to gradually increase weekly exercise duration to 150 minutes per week, per the Physical Activity Guidelines for Americans, with the target heart rate gradually increasing from 40% - 55% to 60% - 75%.2 The control group engaged in nonaerobic exercises that rotated weekly and included core strengthening, use of resistance bands, tai chi, and yoga.

Although the primary outcomes regarding memory, executive function, and depressive symptoms were not met, aerobic exercise was associated with a modest but statistically significant gain in functional ability compared with nonaerobic stretching and toning (P = .02). Disability Assessment for Dementia scores increased 1.5 points for the aerobic group but decreased by 4.5 points for the nonaerobic exercise group. Change in cardiorespiratory fitness, as measured by change in peak VO2, positively correlated with change in memory performance (P = .003). A positive change (P = .03) in bilateral hippocampal volume also was seen.

The bottom line

The researchers noted that the intervention had a meaningful effect on sustained independence. They concluded that their research supports previously published findings on the role of cardiovascular fitness in dementia risk prevention and that regular, supervised aerobic exercise that meets the Physical Activity Guidelines for Americans (2½ hours per week) can help increase functional ability and enhance brain structure in older adults in cognitive decline.